Choice of volatile anesthetic for the morbidly obese patient: sevoflurane or desflurane

Reducing the carbon footprint of general anaesthesia: a comparison of total intravenous anaesthesia vs. a mixed anaesthetic strategy in 47,157 adult patients

Global warming is a major public health concern. Volatile anaesthetics are greenhouse gases that increase the carbon footprint of healthcare. Modelling studies indicate that total intravenous anaesthesia is less carbon intensive than volatile anaesthesia, with equivalent quality of care. In this observational study, we aimed to apply the findings of previous modelling studies to compare the carbon footprint per general anaesthetic of an exclusive TIVA strategy vs. a mixed TIVA-volatile strategy. This comparative retrospective study was conducted over 2 years in two French hospitals, one using total intravenous anaesthesia only and one using a mixed strategy including both intravenous and inhalation anaesthetic techniques. Based on pharmacy procurement records, the quantity of anaesthetic sedative drugs was converted to carbon dioxide equivalents. The primary outcome was the difference in carbon footprint of hypnotic drugs per intervention between the two strategies. From 1 January 2021 to 31 December 2022, 25,137 patients received general anaesthesia in the hospital using the total intravenous anaesthesia strategy and 22,020 in the hospital using the mixed strategy. The carbon dioxide equivalent footprint of hypnotic drugs per intervention in the hospital using the total intravenous anaesthesia strategy was 20 times lower than in the hospital using the mixed strategy (emissions of 2.42 kg vs. 48.85 kg carbon dioxide equivalent per intervention, respectively). The total intravenous anaesthesia strategy significantly reduces the carbon footprint of hypnotic drugs in general anaesthesia in adult patients compared with a mixed strategy. Further research is warranted to assess the risk-benefit ratio of the widespread adoption of total intravenous anaesthesia.

Systematic review with meta-analysis of relative risk of prolonged times to tracheal extubation with desflurane versus sevoflurane or isoflurane

The objective of this systematic review was to estimate the relative risk of prolonged times to tracheal extubation with desflurane versus sevoflurane or isoflurane. Prolonged times are defined as ≥15 min from end of surgery (or anesthetic discontinuation) to extubation in the operating room. They are associated with reintubations, naloxone and flumazenil administration, longer times from procedure end to operating room exit, greater differences between actual and scheduled operating room times, longer times from operating room exit to next case start, longer durations of the workday, and more operating room personnel idle while waiting for extubation. Published randomized clinical trials of humans were included. Generalized pivotal methods were used to estimate the relative risk of prolonged extubation for each study from reported means and standard deviations of extubation times. The relative risks were combined using DerSimonian-Laird random effects meta-analysis with Knapp-Hartung adjustment. From 67 papers, there were 78 two-drug comparisons, including 5167 patients. Studies were of high quality (23/78) or moderate quality (55/78), the latter due to lack of blinding of observers to group assignment and/or patient attrition because patients were extubated after operating room exit. Desflurane resulted in a 65% relative reduction in the incidence of prolonged extubation compared with sevoflurane (95% confidence interval 49% to 76%, P < .0001) and in a 78% relative reduction compared with isoflurane (58% to 89%, P = .0001). There were no significant associations between studies' relative risks and quality, industry funding, or year of publication (all six meta-regressions P ≥ .35). In conclusion, when emergence from general anesthesia with different drugs are compared with sevoflurane or isoflurane, suitable benchmarks quantifying rapidity of emergence are reductions in the incidence of prolonged extubation achieved by desflurane, approximately 65% and 78%, respectively. These estimates give realistic context for interpretation of results of future studies that compare new anesthetic agents to current anesthetics.

The science behind banning desflurane: A narrative review

Potent inhaled anaesthetics are halogenated hydrocarbons with a large global warming effect. The use of fluorinated hydrocarbons (most are not anaesthetics) are being restricted but volatile anaesthetics have been exempted from legislation, until now: the EU has formulated a proposal to ban or at least severely restrict the use of desflurane starting January 2026. This narrative review addresses the implications of a politics-driven decision - without prior consultation with major stakeholders, such as the European Society of Anaesthesiology and Intensive Care (ESAIC) - on daily anaesthesia practice and reviews the potential scientific arguments that would support stopping the routine use of desflurane in anaesthetic practice. Of note, banning or severely restricting the use of one anaesthetic agent should not distract the user from sensible interventions like reducing fresh gas flows and developing technology to capture and recycle or destroy the wasted potent inhaled anaesthetics that we will continue to use. We call to join efforts to minimise our professional environmental footprint.

Postoperative Recovery Outcomes for Obese Patients Undergoing General Anesthesia: A Meta-Analysis of Randomized Controlled Trials

Purpose

This study was performed to assess the postoperative recovery outcomes in obese patients undergoing general anesthesia.

Methods

The eligible studies were identified from PubMed, EmBase, and the Cochrane library until December 2020. The standard mean differences (SMDs) with 95% confidence intervals (CIs) were used to calculate the role of desflurane, sevoflurane, and propofol on recovery outcomes, and the analyses using the random-effects model.

Results

Eleven randomized controlled trials involving 713 obese patients undergoing general anesthesia were selected for final meta-analysis. We noted desflurane was associated with a shorter time to eye-opening than sevoflurane (SMD: −0.86; 95% CI, −1.43 to −0.28; P = 0.003). The use of desflurane with shorter time to extubation as compared with propofol (SMD: −1.13; 95% CI, −1.52 to −0.73; P < 0.001) or sevoflurane (SMD: −1.19; 95% CI, −2.15 to −0.22; P = 0.016), while sevoflurane was associated with longer time to extubation as compared with propofol (SMD: 1.47; 95% CI, 1.03 to 1.91; P < 0.001). Desflurane were associated with shorter time to stating name as compared with propofol (SMD: −1.40; 95% CI, −2.32 to −0.48; P = 0.003) or sevoflurane (SMD: −2.09; 95% CI, −3.33 to −0.85; P = 0.001). In addition, desflurane was associated with a longer time for orientation to place as compared with propofol (SMD: 0.65; 95% CI, 0.22 to 1.07; P = 0.003), while desflurane with shorter time for orientation to place as compared with sevoflurane (SMD: −0.88; 95% CI, −1.46 to −0.30; P = 0.003).

Conclusions

The use of desflurane could provide better recovery outcomes in obese patients undergoing general anesthesia. Further large-scale trials should be comparison the long-term effectiveness of various anesthetics.

A review on the anesthetic management of obese patients undergoing surgery

There has been an observed increase in theprevalence of obesity over the past few decades. The prevalence of anesthesiology related complications is also observed more frequently in obese patients as compared to patients that are not obese. Due to the increased complications that accompany obesity, obese patients are now more often requiring surgical interventions. Therefore, it is important that anesthesiologists be aware of this development and is equipped to manage these patients effectively and appropriately. As a result, this review highlights the effective management of obese patients undergoing surgery focusing on the preoperative, perioperative and postoperative care of these patients.

Recovery Profiles of Sevoflurane and Desflurane with or without M-Entropy Guidance in Obese Patients: A Randomized Controlled Trial

Obesity increases the risk of prolonged emergence from general anesthesia due to the delayed release of anesthetic agents from body fat. This trial aimed to evaluate the effects of sevoflurane and desflurane along with anesthetic depth monitoring on emergence time from anesthesia in obese patients. Adults with a body mass index ≥ 30 kg·m⁻² undergoing laparoscopic sleeve gastrectomy at a medical center were randomized into four groups: sevoflurane or desflurane anesthesia with or without M-Entropy guidance on anesthetic depth in a ratio of 1:1:1:1. In the M-Entropy guidance groups, the dosage of sevoflurane and desflurane was adjusted to achieve response and state entropy values between 40 and 60 during surgery. In the non-M-Entropy guidance groups, the dosage of anesthetics was titrated according to clinical signs. Primary outcome was time to spontaneous eye opening. A total of 80 participants were randomized. Compared to sevoflurane, desflurane anesthesia significantly reduced the time to spontaneous eye opening [mean difference (MD): −129 s; 95% confidence interval (CI): −211, −46], obeying commands (−160; −243, −77), tracheal extubation (−172; −266, −78), and leaving operating room (−148; −243, −54). M-Entropy guidance further reduced time to eye opening (MD: −142 s; 99.2% CI: −276, −8), tracheal extubation (−199; −379, −19), and leaving operating room (−190; −358, −23) in the desflurane but not the sevoflurane group. M-Entropy guidance significantly reduced the risk of agitation during emergence, i.e., risk difference: −0.275 (95% CI: −0.464, −0.086); and number needed to treat: 4. Compared to sevoflurane, using desflurane to maintain general anesthesia accelerated the return of consciousness in obese patients. M-Entropy guidance further hastened awakening in patients using desflurane and prevented emergence agitation.

A comparative study of desflurane versus sevoflurane in obese patients: Effect on recovery profile

Background and Aims:

Anesthesia in obese patients is difficult due to associated comorbidities and altered physiology. Desflurane and sevoflurane have a low fat-blood solubility coefficient and are better suited in these patients to achieve a rapid emergence. We studied BIS guided drug titration to compare the postoperative recovery characteristics and cognitive function of desflurane versus sevoflurane in obese patients undergoing laparoscopic abdominal surgeries.

Material and Methods:

After institutional ethics committee approval and written informed consent, sixty obese patients (BMI ≥30 kg/m²) were randomized to receive either BIS guided desflurane or sevoflurane. Recovery was assessed by time taken for eye opening on verbal command, sustained head lift for 5 s, and extubation and orientation to time, place, and person after discontinuation of volatile anesthetic agent. For cognitive function, time taken to complete Mini mental state examination (MMSE) score to baseline was compared in both study groups.

Results:

Difference of time taken for eye opening on verbal command, sustained head lift for 5 s, and extubation and orientation to time, place, and person was not significant between both anesthetic groups. Patients in sevoflurane group took significantly (P-value = 0.001) less time (40.07 ± 13 min) to achieve preoperative MMSE score than desflurane group (51.2 ± 11.7 min).

Conclusion:

Both desflurane and sevoflurane have similar recovery profile in obese patients when anesthetic concentration is carefully titrated. Reversal of cognitive function is significantly earlier in obese patients anesthetized with sevoflurane.

Context-sensitive decrement times for inhaled anesthetics in obese patients explored with Gas Man®

Anesthesia care providers and anesthesia decision support tools use mathematical pharmacokinetic models to control delivery and especially removal of anesthetics from the patient's body. However, these models are not able to reflect alterations in pharmacokinetics of volatile anesthetics caused by obesity. The primary aim of this study was to refine those models for obese patients. To investigate the effects of obesity on the elimination of desflurane, isoflurane and sevoflurane for various anesthesia durations, the Gas Man® computer simulation software was used. Four different models simulating patients with weights of 70 kg, 100 kg, 125 kg and 150 kg were constructed by increasing fat weight to the standard 70 kg model. For each modelled patient condition, the vaporizer was set to reach quickly and then maintain an alveolar concentration of 1.0 minimum alveolar concentration (MAC). Subsequently, the circuit was switched to an open (non-rebreathing) circuit model, the inspiratory anesthetic concentration was set to 0 and the time to the anesthetic decrements by 67% (awakening times), 90% (recovery times) and 95% (resolution times) in the vessel-rich tissue compartment including highly perfused tissue of the central nervous system were determined. Awakening times did not differ greatly between the simulation models. After volatile anesthesia with sevoflurane and isoflurane, awakening times were lower in the more obese simulation models. With increasing obesity, recovery and resolution times were higher. The additional adipose tissue in obese simulation models did not prolong awakening times and thus may act more like a sink for volatile anesthetics. The results of these simulations should be validated by comparing the elimination of volatile anesthetics in obese patients with data from our simulation models.

Titration of sevoflurane anesthesia to optimize the time to regain airway reflexes in patients undergoing elective surgery: A randomized clinical trial comparing desflurane and sevoflurane anesthesia

BACKGROUND

Desflurane has adverse environmental effects, but has clinical advantages to speed emergence and return of protective airway reflexes compared with sevoflurane. We hypothesized that weaning of the inspired sevoflurane during the final 15 minutes of surgery would eliminate differences in airway reflex recovery between these agents.

METHODS

After obtaining IRB approval and informed consent, 40 patients undergoing elective surgery (≥1-hour) randomly received desflurane or sevoflurane. Patients swallowed 20 mL of water without drooling or coughing, and then received sedation and PONV pre-medication. Anesthesia was induced using propofol and fentanyl and maintained with desflurane or sevoflurane through a laryngeal mask airway maintaining a bispectral index of 45-50 and 50-60 during the final 15 minutes before surgery end. Cardiorespiratory variables and age-adjusted minimal alveolar concentration were recorded. The duration between anesthetic discontinuation and first appropriate response to command was measured; the laryngeal mask airway was removed. Two minutes after responding to command, patients were positioned semi-upright and attempted to swallow water. If successful swallowing was not achieved, the test was repeated every 4 minutes after each failure until successful swallowing was achieved.

RESULTS

Average anesthetic concentration and bispectral index was similar in patients receiving desflurane vs sevoflurane. Response times after discontinuation of anesthetics were similar. There were no differences in the recovery of swallowing ability between desflurane and sevoflurane groups.

CONCLUSION

Weaning of sevoflurane during the final 15 minutes of surgery eliminates clinical advantages of the more rapid return of airway reflexes with desflurane.

Society of Anesthesia and Sleep Medicine Guideline on Intraoperative Management of Adult Patients With Obstructive Sleep Apnea

The purpose of the Society of Anesthesia and Sleep Medicine Guideline on Intraoperative Management of Adult Patients With Obstructive Sleep Apnea (OSA) is to present recommendations based on current scientific evidence. This guideline seeks to address questions regarding the intraoperative care of patients with OSA, including airway management, anesthetic drug and agent effects, and choice of anesthesia type. Given the paucity of high-quality studies with regard to study design and execution in this perioperative field, recommendations were to a large part developed by subject-matter experts through consensus processes, taking into account the current scientific knowledge base and quality of evidence. This guideline may not be suitable for all clinical settings and patients and is not intended to define standards of care or absolute requirements for patient care; thus, assessment of appropriateness should be made on an individualized basis. Adherence to this guideline cannot guarantee successful outcomes, but recommendations should rather aid health care professionals and institutions to formulate plans and develop protocols for the improvement of the perioperative care of patients with OSA, considering patient-related factors, interventions, and resource availability. Given the groundwork of a comprehensive systematic literature review, these recommendations reflect the current state of knowledge and its interpretation by a group of experts at the time of publication. While periodic reevaluations of literature are needed, novel scientific evidence between updates should be taken into account. Deviations in practice from the guideline may be justifiable and should not be interpreted as a basis for claims of negligence.

Intraoperative immunomodulatory effects of sevoflurane versus total intravenous anesthesia with propofol in bariatric surgery (the OBESITA trial): study protocol for a randomized controlled pilot trial

Background

Obesity is associated with a chronic systemic inflammatory process. Volatile or intravenous anesthetic agents may modulate immune function, and may do so differentially in obesity. However, no study has evaluated whether these potential immunomodulatory effects differ according to type of anesthesia in obese patients undergoing laparoscopic bariatric surgery.

Methods/design

The OBESITA trial is a prospective, nonblinded, single-center, randomized, controlled clinical pilot trial. The trial will include 48 patients with a body mass index ≥ 35 kg/m², scheduled for laparoscopic bariatric surgery using sleeve or a Roux-en-Y gastric bypass technique, who will be allocated 1:1 to undergo general inhalational anesthesia with sevoflurane or total intravenous anesthesia (TIVA) with propofol. The primary endpoint is the difference in plasma interleukin (IL)-6 levels when comparing the two anesthetic agents. Blood samples will be collected prior to anesthesia induction (baseline), immediately after anesthetic induction, and before endotracheal extubation. Levels of other proinflammatory and anti-inflammatory cytokines, neutrophil chemotaxis, macrophage differentiation, phagocytosis, and occurrence of intraoperative and postoperative complications will also be evaluated.

Discussion

To our knowledge, this is the first randomized clinical trial designed to compare the effects of two different anesthetics on immunomodulation in obese patients undergoing laparoscopic bariatric surgery. Our hypothesis is that anesthesia with sevoflurane will result in a weaker proinflammatory response compared to anesthesia with propofol, with lower circulating levels of IL-6 and other proinflammatory mediators, and increased macrophage differentiation into the M2 phenotype in adipose tissue.

Trial registration

Registro Brasileiro de Ensaios Clínicos, RBR-77kfj5. Registered on 25 July 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3399-z) contains supplementary material, which is available to authorized users.

Comparison of the Recovery Profile between Desflurane and Sevoflurane in Patients Undergoing Bariatric Surgery-a Meta-Analysis of Randomized Controlled Trials

Early and clear recovery from anesthesia is the crux for preventing perioperative complications in the obese undergoing bariatric surgery. Volatile inhalation agents by virtue of high lipid solubility are expected to produce residual anesthetic effects. Prospective randomized trials comparing desflurane and sevoflurane used for anesthesia maintenance (electroencephalograph guided) during bariatric surgery published till 1st of July 2017 were searched in the medical database. Comparisons were made for surrogate markers of recovery from anesthesia that included time to eye-opening (TEo), time to tracheal-extubation (TEx), and Aldrete scores on immediately shifting to recovery (Ald-I). Five trials were included in the final analysis. Patients receiving desflurane began to respond faster by opening eyes on command (five trials) by 3.80 min (95%CI being 1.83-5.76) (random effects, P < 0.01, I² = 78.61%), and tracheal extubation was also performed earlier (four trials) by 4.97 min (95%CI being 1.34-8.59). This meant a reduction of 37% in TEo and 33.60% in TEx over sevoflurane. Ald-I scores were higher/better with desflurane by 0.52 (95%CI being 0.19-0.84) (Fixed-effects, P < 0.01, I² = 6.67%). Publication bias is likely for TEo (Egger's Test, X-intercept = - 8.57, P = 0.02). No airway-related complications were reported with desflurane's expedited recovery. Use of desflurane compared to sevoflurane for maintenance of anesthesia in morbidly obese patients allows attaining verbal contact faster, and tracheal extubating can be performed earlier without compromising safety. The benefits of better recovery extend into the immediate postoperative phase with patients being more awake upon shifting to the recovery.

Perioperative management of the obese surgical patient

INTRODUCTION

The escalation in the prevalence of obesity throughout the world has led to an upsurge in the number of obese surgical patients to whom perioperative care needs to be delivered.

SOURCES OF DATA

After determining the scope of the review, the authors used PubMed with select phrases encompassing the words in the scope. Both preclinical and clinical reports were considered.

AREAS OF AGREEMENT

There were no controversies regarding preoperative management and the intraoperative care of the obese surgical patient.

AREAS OF CONTROVERSY

Is there a healthy obese state that gives rise to the obesity paradox regarding postoperative complications?

GROWING POINTS

This review considers how to prepare for and manage the obese surgical patient through the entire spectrum, from preoperative assessment to possible postoperative intensive care.

AREAS TIMELY FOR DEVELOPING RESEARCH

What results in an obese patient developing 'unhealthy' obesity?

Immunomodulatory effects of anesthetics in obese patients

Anesthesia and surgery have an impact on inflammatory responses, which influences perioperative homeostasis. Inhalational and intravenous anesthesia can alter immune-system homeostasis through multiple processes that include activation of immune cells (such as monocytes, neutrophils, and specific tissue macrophages) with release of pro- or anti-inflammatory interleukins, upregulation of cell adhesion molecules, and overproduction of oxidative radicals. The response depends on the timing of anesthesia, anesthetic agents used, and mechanisms involved in the development of inflammation or immunosuppression. Obese patients are at increased risk for chronic diseases and may have the metabolic syndrome, which features insulin resistance and chronic low-grade inflammation. Evidence has shown that obesity has adverse impacts on surgical outcome, and that immune cells play an important role in this process. Understanding the effects of anesthetics on immune-system cells in obese patients is important to support proper selection of anesthetic agents, which may affect postoperative outcomes. This review article aims to integrate current knowledge regarding the effects of commonly used anesthetic agents on the lungs and immune response with the underlying immunology of obesity. Additionally, it identifies knowledge gaps for future research to guide optimal selection of anesthetic agents for obese patients from an immunomodulatory standpoint.

A clinical review of inhalation anesthesia with sevoflurane: from early research to emerging topics

A large number of studies during the past two decades have demonstrated the efficacy and safety of sevoflurane across patient populations. Clinical researchers have also investigated the effects of sevoflurane, its hemodynamic characteristics, its potential protective effects on several organ systems, and the incidence of delirium and cognitive deficiency. This review examines the clinical profiles of sevoflurane and other anesthetic agents, and focuses upon emerging topics such as organ protection, postoperative cognitive deficiency and delirium, and novel ways to improve postanesthesia outcomes.

Perioperative Pharmacologic Considerations in Obesity

Obesity has increased in incidence worldwide. Along with the increased number of obese patients, comorbid conditions are also more prevalent in this population. Obesity leads to changes in the physiology of patients along with an altered response to pharmacologic therapy. Vigilant perioperative physicians must be aware of the unique characteristics of administered agents in order to appropriately provide anesthetic care for obese patients. Because of the variability in tissue content in obese patients and changes in pharmacokinetic modeling, a one-size-fits-all approach is not justified and a more sophisticated and prudent approach is indicated.

Effects of avoiding neuromuscular blocking agents during maintenance of anaesthesia on recovery characteristics in patients undergoing craniotomy for supratentorial lesions: A randomised controlled study

Background and Aims:

Neuromuscular blocking agents have been one of the cornerstones of anaesthesia. With the advent of newer surgical, anaesthetic and neurological monitoring techniques, their utility in neuroanaesthesia practice seems dispensable. The aim of this prospective, comparative, randomised study was to determine whether neuromuscular blocking agents are required in patients undergoing supratentorial surgery when balanced anaesthesia with desflurane, dexmedetomidine and scalp block is used.

Methods:

Sixty patients with the American Society of Anesthesiologists physical status I or II, aged between 18 and 60 years were included in the study. All patients received anaesthesia including desflurane, dexmedetomidine and scalp block. The patients were randomly allocated to receive no neuromuscular blocking agent (Group A) or atracurium infusion to keep train-of-four count 2 (Group B). The two groups were compared with respect to haemodynamic stability, brain relaxation scores and recovery characteristics. Haemodynamic parameters and time taken to achieve Aldrete score >9 and other secondary outcomes were analysed using Student's t-test. Non-parametric data were analysed using the Mann–Whitney test.

Results:

The mean arterial pressure was comparable between the groups. The intraoperative heart rate was comparable; however, in the post-operative period, it remained higher in Group B for 30 min after extubation (P = 0.02). The brain relaxation scores were comparable among the two groups (P = 0.27). Tracheal extubation time, time taken for orientation and time required to reach Aldrete score ≥9 were comparable among the two groups.

Conclusion:

The present study suggests that balanced anaesthesia using desflurane, dexmedetomidine and scalp block can preclude the use of neuromuscular blocking agents in patients undergoing supratentorial surgery under intense haemodynamic monitoring.

Postoperative recovery after anesthesia in morbidly obese patients: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Obese patients present a challenge to safe general anesthesia because of impaired cardiopulmonary physiology and increased risks of aspiration and acute upper airway obstruction. Since studies are lacking regarding the postoperative effects on recovery from general anesthesia in morbidly obese patients, we conducted a systematic review and meta-analysis of recovery outcomes in morbidly obese patients who had undergone general anesthesia.

SOURCE

We systematically searched the PubMed, EMBASE™, Cochrane, and Scopus™ databases for randomized controlled trials that evaluated the outcome of anesthesia with desflurane, sevoflurane, isoflurane, or propofol in morbidly obese patients. Using a random effects model, we conducted meta-analyses to assess recovery times (eye opening, hand squeezing, tracheal extubation, and stating name or birth date), time to discharge from the postanesthesia care unit (PACU), and the incidence and severity of postoperative nausea and vomiting (PONV).

PRINCIPAL FINDINGS

We reviewed results for 11 trials and found that patients given desflurane took less time: to respond to commands to open their eyes (weighted mean difference [WMD] -3.10 min; 95% confidence interval (CI): -5.13 to -1.08), to squeeze the investigator's hand (WMD -7.83 min; 95% CI: -8.81 to -6.84), to be prepared for tracheal extubation (WMD -3.88 min; 95% CI: -7.42 to -0.34), and to state their name (WMD -7.15 min; 95% CI: -11.00 to -3.30). We did not find significant differences in PACU discharge times, PONV, or the PACU analgesic requirement.

CONCLUSION

Postoperative recovery was significantly faster after desflurane than after sevoflurane, isoflurane, or propofol anesthesia in obese patients. No clinically relevant differences were observed regarding PACU discharge time, incidence of PONV, or postoperative pain scores. The systematic review was registered with PROSPERO (CRD42014009480).

Anesthetic drugs and bariatric surgery

The prevalence of obesity is increasing worldwide. For severely obese patients, bariatric surgery is the only effective option for sustained weight loss and associated health improvement. As a consequence, the number of bariatric surgical procedures being performed is growing exponentially. Systematic knowledge regarding the effect of obesity on the pharmacokinetics and pharmacodynamics of anesthetic agents is generally lacking, and data for morbidly obese (body mass index [BMI] 40-49 kg/m2)) and super-obese patients (BMI > 50 kg/m2) are almost completely non-existent. Most drug-dosing guidelines are based on results from relatively small studies in moderately obese patients. Future systematic pharmacological research is needed for improved and more rational peri-operative care of morbidly obese patients.

Anesthetic Pharmacology and the Morbidly Obese Patient

Anesthesiologists are increasingly being faced with treating obese patients. Physiologic and anthropometric associated with obesity-most notably increases in cardiac output, changes in tissue perfusion and increases in total body weight (TBW), lean body weight (LBW), and fat mass affect the pharmacokinetics (PK) of anesthetic agents. In addition, redundancy of airway tissue, obstructive and central sleep apnea and CO2 retention affect the pharmacodynamics (PD) of anesthetics and narrow the therapeutic window of numerous anesthetic drugs. Safe and effective pharmacologic management of the obese patient requires a thorough understanding of how obesity affects the PK and PD of anesthetics.

Desflurane: a clinical update of a third-generation inhaled anaesthetic

Available volatile anaesthetics are safe and efficacious; however, their varying pharmacology provides small but potentially clinically important differences. Desflurane is one of the third-generation inhaled anaesthetics. It is the halogenated inhaled anaesthetic with the lowest blood and tissue solubilities, which promotes its rapid equilibration and its rapid elimination following cessation of administration at the end of anaesthesia. The low fat solubility of desflurane provides pharmacological benefits, especially in overweight patients and in longer procedures by reducing slow compartment accumulation. A decade of clinical use has provided evidence for desflurane's safe and efficacious use as a general anaesthetic. Its benefits include rapid and predictable emergence, and early recovery. In addition, the use of desflurane promotes early and predictable extubation, and the ability to rapidly transfer patients from the operating theatre to the recovery area, which has a positive impact on patient turnover. Desflurane also increases the likelihood of patients, including obese patients, recovering their protective airway reflexes and awakening to a degree sufficient to minimise the stay in the high dependency recovery area. The potential impact of the rapid early recovery from desflurane anaesthesia on intermediate and late recovery and resumption of activities of daily living requires further study.

Obesity and Obstetric Anaesthesia

Obesity is increasing in the population as a whole, and especially in the obstetric population, among whom pregnancy-induced physiological changes impact on those already present due to obesity. In particular, changes in the cardiovascular and respiratory systems during pregnancy further alter the physiological effects and comorbidities of obesity. Obese pregnant women are at increased risk of diabetes, hypertensive disorders of pregnancy, ischaemic heart disease, congenital malformations, operative delivery, postpartum infection and thromboembolism. Regional analgesia and anaesthesia is usually preferred but may be challenging. Obese pregnant women appear to have increased morbidity and mortality associated with caesarean delivery and general anaesthesia for caesarean delivery in particular, and more anaesthesia-related complications. This article summarises the physiological and pharmacological implications of obesity and pregnancy and describes the issues surrounding the management of these women for labour and delivery.

Anesthetizing the obese child

The prevalence of childhood obesity is increasing. The focus of this review is the special anesthetic considerations regarding the perioperative management of obese children. With obesity the risk of comorbidity such as asthma, obstructive sleep apnea, hypertension, and diabetes increases. The obese child has an increased risk of perioperative complications especially related to airway management and ventilation. There is a significantly increased risk of difficult mask ventilation and perioperative desaturation. Furthermore, obesity has an impact on the pharmacokinetics of most anesthetic drugs. This has important implications on how to estimate the optimal drug dose. This article offers a review of the literature on definition, prevalence and the pathophysiology of childhood obesity and provides suggestions on preanesthetic evaluation, airway management and dosage of the anesthetic drugs in these patients. The authors highlight the need of supplemental studies on various areas of the subject.

A randomised trial comparing sufentanil versus remifentanil for laparoscopic gastroplasty in the morbidly obese patient

BACKGROUND AND OBJECTIVE

This prospective, randomised double-blind study compared the effects of target control infusion (TCI) of sufentanil and remifentanil on the quality of recovery and post-operative pain control in morbidly obese patients undergoing laparoscopic gastroplasty.

METHODS

Following institutional Ethics Committee approval and written informed consent, 100 morbidly obese patients were randomised to receive either TCI sufentanil (0.3 ng ml⁻¹; S-group; N = 50) or TCI remifentanil (3 ng ml⁻¹; R-group; N = 50) in combination with desflurane (O₂/air mixture: FiO₂, 50%). Quality of recovery was estimated by means of the modified Aldrete score and by the ability to perform psychomotor tests with the same competence post-operatively as pre-operatively. Post-operative pain was evaluated by the quantity of piritramide needed to achieve a visual analogue scale (VAS) less than 3. Statistical analysis was performed using an unpaired Student's t-test, Mann-Whitney U-test and χ² test, as appropriate.

RESULTS

Patient and surgical characteristics were similar among groups. In the R-group, time to extubation was significantly shorter, but VAS significantly higher than that in the S-group (P < 0.01). Quality of recovery and duration of post-anaesthesia care unit stay were comparable between groups (S-group: 119 ± 27 min and R-group: 119 ± 35 min). Piritramide consumption during the first 4 post-operative hours was higher in the R-group than in the S-group [S-group (median, range): 11.5 mg, 5.5-16.0; R-group: 18.0 mg, 14-22, P < 0.01], but not later on.

CONCLUSION

In the conditions of the present study, although TCI sufentanil resulted in slower awakening than TCI remifentanil, it was associated with a better quality of recovery.

Anaesthesia in the obese child

The incidence of childhood obesity ranges today from approximately 8% to 17%, and is an increasing issue in developed and developing countries. This disease will become increasingly significant in paediatric anaesthesia. Obese children not only have anaesthesia-relevant co-existing diseases, that are, asthma and hypertension, but also have a higher incidence of anaesthesia-related complication. This review covers current definition and some epidemiology of childhood obesity. It summarises potential co-morbidities and provides details for preoperative evaluation, anaesthetic management and prevention of perioperative complications.

Anaesthesia for bariatric surgery

Although many smaller studies have addressed anaesthetic care for bariatric surgical patients, comprehensive systematic literature reviews have yet to be compiled, and much evidence includes expert panel opinion. This review summarises study results in bariatric surgical patients regarding pre-anaesthesia evaluation, the perioperative impact of sleep-disordered breathing, airway management at anaesthetic induction and emergence, maintenance of anaesthesia, postoperative pain management, utility of clinical-care pathways and feasibility of outpatient bariatric surgery. The 'ramped' upper-body, reversed Trendelenburg position at anaesthetic induction and manual application of positive end-expiratory pressure (PEEP) is recommended. Intra-operative hypoxaemia can be treated with the combination of PEEP and recruitment manoeuvres, and attention to airway management at emergence is critical. Local anaesthetic wound infiltration and non-steroidal anti-inflammatory drugs should be part of multimodal opioid-sparing postoperative analgesia. Implementation of bariatric clinical-care pathways seems beneficial. Considering the prevalence of sleep apnoea in these patients, outpatient bariatric surgery remains controversial, but is probably safe for certain procedures, provided there is strict adherence to preoperative eligibility and home-care protocols.

Update on best practice recommendations for anesthetic perioperative care and pain management in weight loss surgery, 2004-2007

To reevaluate and update evidence-based best practice recommendations published in 2004 for anesthetic perioperative care and pain management in weight loss surgery (WLS), we performed a systematic search of English-language literature on anesthetic perioperative care and pain management in WLS published between April 2004 and May 2007 in MEDLINE and the Cochrane Library. We identified relevant abstracts by using key words, retrieved full text articles, and stratified the resulting evidence according to systems used in established evidence-based models. We updated prior evidence-based best practice recommendations based upon interim literature. In instances of controversial or inadequate scientific evidence, the task force reached consensus recommendations following evaluation of the best available information and expert opinion. The search yielded 1,788 abstracts, with 162 potentially relevant titles; 45 were reviewed in detail. Despite more information on perioperative management of patients with obstructive sleep apnea (OSA), evidence to support preoperative testing and treatment or to guide perioperative monitoring is scarce. New evidence on appropriate intraoperative dosing of muscle relaxants allows for greater precision in their use during WLS. A novel application of alpha-2 agonists for perioperative anesthetic care is emerging. Key elements that may enhance patient safety include integration of the latest evidence on WLS, obesity, and collaborative multidisciplinary care into clinical care. However, large gaps remain in the evidence base.

Faster wash-out and recovery for desflurane vs sevoflurane in morbidly obese patients when no premedication is used

BACKGROUND

The aim of this study was to compare desflurane vs sevoflurane kinetics and dynamics in morbidly obese patients and their recovery profile when no premedication had been used.

METHODS

Twenty-eight unpremedicated obese patients were randomly allocated to receive either sevoflurane (n = 14) or desflurane (n = 14) as the main anaesthetic agent. After induction of anaesthesia, either sevoflurane 2% or desflurane 6% was administered for 30 min via a non-rebreathing circuit. The kinetics of sevoflurane and desflurane were determined by measuring and recording end-tidal samples during this time. The bispectral index was used to indicate the level of hypnosis. At the end of the procedure, the end-tidal concentrations of sevoflurane and desflurane were recorded during the first 5 min after stopping their administration. Time from discontinuation of the anaesthetic drugs to eye opening on verbal command, squeezing the observer's hand on command, extubation, stating their name, giving their correct date of birth, discharge from the recovery room, and duration of the surgery and anaesthesia were also recorded.

RESULTS

The F(A)/F(I) ratio was significantly higher in the desflurane group from the 15th to the 30th min. The wash-out phase was faster for desflurane during the total observation period. When desflurane was used, recovery was also faster.

CONCLUSIONS

Desflurane provides faster wash-in and wash-out than sevoflurane in morbidly obese patients, and recovery is much faster after desflurane administration when no premedication has been used.

Influence of intraoperative opioid on postoperative pain and pulmonary function after laparoscopic gastric banding: remifentanil TCI vs sufentanil TCI in morbid obesity

BACKGROUND

Choice of opioid may influence postoperative pain, recovery, and respiratory homeostasis in morbid obesity. The aim of this study was to compare the effects of target-controlled infusions (TCIs) of remifentanil or sufentanil on postoperative analgesia, recovery, and pulmonary function after laparoscopic gastric banding.

METHODS

Forty morbidly obese patients undergoing laparoscopic gastric banding received BIS-guided desflurane anaesthesia combined with remifentanil TCI (Group R) or sufentanil TCI (Group S). Intraoperative haemodynamic stability, BIS controllability, and immediate recovery in the operating room were measured. Pulmonary function, modified Aldrete score, modified Observers Assessment of Alertness and Sedation score, blood gas analysis, and visual analogue score for pain and postoperative nausea and vomiting were measured on admission to the post-anaesthesia care unit and 30, 60, 120 min afterwards. After operation, patients received patient-controlled analgesia with morphine.

RESULTS

During the first two postoperative hours, cumulative morphine consumption was higher in the remifentanil group compared with the sufentanil group, but was equal values after that time. Recovery profiles and spirometry showed no significant differences. During maintenance, remifentanil gave a better haemodynamic stability.

CONCLUSIONS

As few differences occurred in the postoperative period, the theoretical advantage of remifentanil over the longer acting sufentanil can be questioned when using TCI technology.

Desflurane versus sevoflurane for laparoscopic gastroplasty in morbidly obese patients

STUDY OBJECTIVE

To determine if desflurane results in a faster emergence as measured by time to eye opening compared to sevoflurane in morbidly obese patients undergoing laparoscopic gastroplasty.

STUDY DESIGN

Prospective, randomized, double-blinded study.

SETTING

Tertiary care hospital.

PATIENTS

70 patients with a body mass index of 35 or higher undergoing laparoscopic gastroplasty.

INTERVENTIONS

Patients were randomized into two groups to receive either desflurane or sevoflurane for maintenance of general anesthesia.

MEASUREMENTS

Intraoperative measured variables included the time from when the inhalation agent was turned off (no agent delivered) to eye opening and the time from when the inhalation agent was turned off to extubation. Postanesthesia care unit (PACU)-measured variables on admission and at 15 minute intervals until discharge included oxygen saturation (Spo2), blood pressure, heart rate, pain and nausea Visual Analog Scale (VAS) scores, emesis, modified Aldrete score, and Mini-Mental Status (MMS) examination score.

MAIN RESULTS

No differences were noted in demographic data, total surgical operative time, times from turning inhalation agent off to eye opening and extubation, or average length of stay in PACU. No differences were noted with respect to pain VAS, treatment for pain, modified Aldrete scores, emesis, or treatment for postoperative nausea or emesis. Differences were noted in PACU nausea VAS at 15 minutes, PACU nausea VAS at discharge, and PACU-MMS score at 45 minutes; however, multivariate analysis of variance revealed no differences between groups over the repeated PACU measured time periods in nausea VAS (P=0.17) or in MMS (P=0.34). Higher heart rates in the desflurane group were observed during PACU admission (82.3+/-9.8 vs 74.4+/-13.4 bpm, P<0.01) and 15 minutes post PACU admission (79.4+/-12.1 vs 71.3+/-13.2 bpm, P=0.01).

CONCLUSIONS

In morbidly obese patients undergoing laparoscopic gastroplasty, emergence, as measured by time to eye opening, did not differ between desflurane and sevoflurane, with similar recovery characteristics.

Perioperative considerations for patients with morbid obesity

The anesthetic management of the MO patient requires an important focus on a number of issues beginning with a careful preoperative evaluation and synthesizing pre-existing disease processes with the anesthetic management plan. The common misperception that all MO patients are "full stomach" has been challenged and may be a nonissue. New approaches to pre-oxygenation to lessen the likelihood of desaturation during apnea may be a valuable tool if difficulty is encountered in tracheal intubation. In addition, promising results have been demonstrated with the use of the ILMA for ventilation and for blindly establishing tracheal tube placement. Proper patient positioning is essential to aid in successful intubation when a laryngoscope is employed. Intraoperative anesthetic management can be guided with a processed electroencephalogram monitor to help improve emergence and to enhance wakefulness in the PACU. Careful consideration must be given to postoperative analgesic needs by minimizing the use of opioids and employing nonopioid analgesics including NSAIDs, alpha2-adrenergic agonists, and low doses of ketamine.

Anesthesia for thoracic surgery in morbidly obese patients

PURPOSE OF REVIEW

This review considers the anesthetic management of obese patients undergoing thoracic surgery. Extremely or morbidly obese patients differ from patients of normal weight in several ways. Obese patients have altered anatomy and physiology, and usually have associated comorbid medical conditions that may complicate their operative course and increase their risks for postoperative complications.

RECENT FINDINGS

During anesthetic induction and laryngoscopy for tracheal intubation the morbidly obese patient should be in the reverse Trendelenburg position with the head and neck elevated above the table. Placement of a double-lumen tube should be no more difficult in an obese patient than in a normal-weight patient. There are no clear advantages for any of the commonly available inhalational anesthetic agents and each can be used for general anesthesia.

SUMMARY

With proper attention to their special needs, the morbidly obese patient can safely undergo thoracic surgery and one-lung ventilation.